Cold Wave Conditions in North India

What is a cold wave?

• The IMD records a cold wave when the minimum temperature is equal to or less than 10 degree Celsius at a weather station in the plains, and is 5 degrees to 6.4 degrees below the normal temperature for that period.
• A cold wave may also be recorded at a station in the plains when the minimum temperature is less than or equal to 4 degree Celsius.
• For hilly regions, a cold wave is declared when the minimum temperature is less than or equal to 0 degree Celsius and the minimum temperature is 4.5 degrees to 6.4 degrees below the normal.
• The ‘normal’ temperature is calculated for every five days by taking the average temperature for these days over the past 30 years.

Q1) What causes a cold wave?

In the Northern Hemisphere, cold waves occur when very cold, dense air near the surface moves out of its source region in northern Canada or northern Asia.

Source: Severe cold wave conditions to continue in North India till Thursday

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